Stomach and Gastric Acid Secretion

Mucous cell component and its functions

HCO3 and Mucin → Protect the stomach from its acid

Parietal cell component and its functions

Intrinsic factor → Help B12 (cobalamin) absorption, HCl → Stomach acid

Chief cell component and its function

Pepsinogen → Activate by HCl to break down protein; gastric lipase → Digest fat

G cell function

Secrete gastrin to activate ECL and parietal cell → More acid secretion

D cell function

Secrete somatostatin that INHIBIT parietal cell and G cell → Decrease acid secretion

ECL cell function

Secrete histamine → stimulate parietal cell to secrete HCl

What are oxyntic glands

80% of glands in stomach found in all areas EXCEPT pylorus

What are pyloric glands

20% of glands in stomach found ONLY in pylorus

What cell can be found in the oxyntic gland that is not found in pyloric

Parietal, ECL, chief cell → All function to INCREASE stomach acid and digest

Why is mucus and HCO3 important in protecting the stomach

Mucus creates a protective layer to stop acid from destroying the wall, HCO3 neutralizes acid

How does H+ enter the gastric secretion

CO2 from blood enter cell → Combine with water to form H2CO3 → Split into H+ and HCO3 → H+ pumped INTO stomach by H/K ATPase → HCO3 pumped back into BLOOD

What do PPI do (proton pump inhibitors)

Inhibit proton pump to PREVENT H+ from entering the stomach

What can regulate gastric acid secretion

Gastrin → Secreted by G cell, histamine → Secreted by ECL, ACh by PNS through vagus

What regulates pepsinogen secretion

S cell release secretin → Activate chief cell to secrete pepsinogen

What are the phases of gastric juice secretion

Cephalic, gastric, intestinal

What is the cephalic phase function

Thought/smell of food causes gastric juice secretion

What is the gastric phase

Secretion of gastrin and histamine to activate parietal cells caused by stomach distension

What is intestinal phase

Gastric secretion decrease, food is sent to duodenum